Electric furnace.



c. FERY an C. LANGLET.

ELECTRIC FURNAGE.

APPLIGMION FILED umso, 1907.

Patented Dec. 13, 1910.

2 SHEETS-SHEET 1.

c. PRY & c. LANGLBT. ELECTRIC PURNACB.

APPLIOA'IION FILED IABLSO, 1907.

Patented Dec. 18, 1910.

2 SHEETS-SHEET 2.

'tions D D of different theoue can slide in the other, vspacebetween the two cylindrical parts is UNITED sTATEs PATENT oEEioE.I

CHARLES FRY AND CHARLES LANGLET,` 0F PARS, FRANCE.

ELECTRIC' FURNACE.

Specification of Letters Patent.

Patented Dec. 131910.

Application led January 30, 1907. Serial N o. 354,866.

Toall whom 'it may concen Be it known that we, CHARLES Friar and CHARLES LANGLET, bot-h citizens of the French Republic, 4and residents of Paris, France, have invented certain Improvements in Electric Furnaces, of which the following is ya specification.

Existing electric resistance furnaces are faulty because the `various parts of which they are constructed expand unequally when heated. They are liable to o n at the joints and in those furnaces wherein thev resistance is of carbon protected by a thick layer of light carbon which is a.v bad conductor of heat and electricity, the air thus admitted renders the protection illusory, considerably diminishing the life of the furnace by burning the carbon resistance. r1 he present invention is designed to eliminate this fault. j

The accompanying drawings illustrate the invention. Figures 1, 2, 5, 6, 9, 10, 11, 12. 15 and 16 are longitudinalsections respectively through modifications of the furnace constructed according to the invention. Figs. 3r

and 4 are transverse sections respectively of two further modifications. Figs. 7 and 8 are an end elevation and a side elevation respectively showing a detail. Figs. 13 and 14' are perspective views of two forms of con ductor for use in furnaces according to this invention.

In a furnace of this kind, the central tube of refractory material is often surrounded by a helical conductor consisting of carbon. In this case the form of the conductor gives a certain amount ofi-elasticity, sufficient to avoid any strain on the joints which unite it to the refractory tube at its ends when expansion occurs. In order that the joints between the carbon conductorand the casing shall be equally imm'une from destruction, the casing according to this invention is made so that it can suffer deformation, that is to say so that it can increase more or less in length, and thus withstand at the joints the strain to which it is subjected owing toV the expansion of the conductor.

As shown in Fig. 1, for instance, the casing may consist of two cylindrical pordialneter, such that The annular `iaclired 'with' asbestos a. When the air inclosed in thc mass of carbon C expands .under the influence of the heat, it (am escape through this joint a, and if'v afterward air should enter again by this path. no harm will be done, because this air will have to 4 tra-verse the mass of carbon C before it can gain access to the carbon conductor B. and

will thus be robbed of its oxygen, so that it cannot attack the conductor B.

In they modification shown in Fig. 2, there is a cylindrical casing D surrounding at each of its ends th'e corresponding cylindrical end pieces D, the intervening spaces being packed with asbestos al.

separate pieces, and to make them slide more jections b as shown in Fig. 3, or they may be made with semi-circular grooves c lin which are placed rollers or balls el as indicated in Fig. 5. If itv is necessary powdered carbon. C from escaping' through the joint a, an asbestos sleeve e may be fastened inside thecylinder D, so that cylinder D may be introduced between this sleeve and cylinder D as shown in Fi 5.

As shown in Fig. 6, the casing D may be made corrugated instead of plain, either as to the whole of its surface, as in the figure, or as to a part thereof. In this case the casing can readily adapt ,itself tothe longitudinal strains due to the expansion ofthe refractory tube A..together with its carbon 'conductor B.

Instead of making the casing in the form of a cylinder, it may be made up of stamped dished rings E,.a pair of which are shown in Figs. 7 and 8. These rings are assembled in the manner indicated in Fig. 9, the object of this formation being to enable the casing to respond readily to the variations in length to which it is subjected. It is obvious that the form of the rings E may be any that is suitable for fulfilling this object. rl`he same result may be obtained by making the casing D cylindrical, and uniting it at the ends to the carbon conexample as shown in Fig. 10, of circularly corrugated disks, similar to those which makeup the box of an aneroid barometer.

Fig. 11 shows a variation of this form, in which the cheeks F are curved so as to allow of the expansion and contraction of the cylinder D. These cheeks` can be united to the cylinder D by means of cylindrical flanges f, or these lianges may be left free to slide on the ends of the cylinder so that Vthe gases can escape by the narrow passages In order to, facilitate the relative movement of --these to prevent the ,ductor B by elastic cheeks F formed for formed between the iianges of the cylinder, or if it is preferable to make the joint at these. parts tight, a small hole can be pierced in the cylinder to serve the same purpose.

In a muffle furnace or Crucible furnace of this kind, one end only of the mufile or of` thecrucible comes to the open pai-t of the furnace. the other end being free to expand within the mass of powered carbon lunder the influence of the heat. In Fig. 12 there is a inutlie G surrounded by 'a carbon conductor B. itself surrounded by a protecting mass ot' powdered carbon C vcontained within a casing D. If the conductor B is elastic, such as it is for example when made in the forni of a helix, the casing D may be incapable of changing its form without any undue strain on the joint g at the front end of the inutile, or on the joints H which connect the conductor B with the casing C. It is also possible to use a casing incapable of changing its form when the muie and the conductor only communicate with the outside of the furnace at one end thereof, as is the case, for example, when the conductor B is formed of a prismatic bar of carbon (Fig. 13) slotted as at la so as to have more or less the shape of a U. lThe same applies when the conductor is a cylinder slotted at the sides as at m. m, Fig. 14, at opposite ends of a diameter. ln this case the furnace -may be arranged as shown in Fig. 15, the

inutile and the carbon tube (Fig. 14) or the conducting cheeks (Fig. 13) are invariably fixed vat the open end n of the casing D. The opening 71. only serves for the introduction of the protecting powder, and may be at the side of the cylinder instead of4 at the end as shown. In tliis'case the carbon conductor and the mutflc mav expand freely without the necessity for providing a casing which can change its forni.

)Vliatever may be the arrangement to insure free expansion, it is ldesirable to consolidate the joints between the muffle or Crucible, the conductor and the casing, by a collar made in two parts 0 as shown in Fig. 16,.applied to a cylindrical fiange'p formed on the casiiig'D.

Having thus described the nature of our said invention and the best means we know of carry-ing the same into practical effect, we claim 1. An. electric furnace having a heatinga chamber, two members, one of which is an electric conductor adapted to impart heat to said chamber, andthe other of which is a jacket arranged around said conductor,

and a protectingfilling interposed between said members, one of said members being capable of expansion and contraction independently of the other member to compensate for unequal expansion and contraction of the members relatively to each other during the operation of the furnace.

2. An electric furnace having a heating chamber, an electric conductor adapted to impartheat to said chamber, a longitudinally extensible jacket arranged around said conductor, and a protecting filling interposed between the conductor and said jacket.

1. An electric furnace having a heating chamber, an electric conductor adapted to impart heat to said chamber, a jacket arranged around the conductor and provided with elastic heads connected with the conductor, and a protecting filling interposed between the conductor and said jacket.

5. An electric resistance furnace having :a-

heating chamber, an electric conductor surrounding the said chamber, a protecting mass surrounding the said conductor, and a.,

casing surrounding the said protecting mass and having end cheeks that arecorrugated.

G. An electric resistance furnace having a heating chamber, an electric conductor surrounding the said chamber, a protecting mass surrounding the said conductor, and a casing surrounding the said protecting mass and having end cheeks that are fiexible.

ln wit-ness whereof, we have hereunto signed our names in the presence of two subscribing witnesses.

CHARLES FRY. CHARLES LANGLET.. Witnesses H. C. Conn, l GABRIEL BiiLLiAiin. 

